The invention concerns an analytical method for determining crystallographic phases of a measuring sample, wherein a diffraction pattern of the measuring sample and an element spectrum of the measuring sample are acquired.
A method of this type is disclosed in R. Meier and M. Dirken, International Cement & Lime Journal, Issue 2 (2002), pages 18–21.
Information about crystallographic phases in a measuring sample can be obtained with diffraction experiments, such as e.g. X-ray diffraction (XRD), electron diffraction or neutron diffraction. Towards this end, a focussed or paralleled, essentially monochromatic beam of X-rays, electrons, or neutrons is directed onto the measuring sample and the diffracted beam (or the diffracted rays) is registered by a detector. The position of the diffracted rays provides information concerning the qualitative composition of the measuring sample, and the intensity provides information concerning the portion (concentration) of the respective phases.
Qualitative and quantitative analysis using diffraction experiments may be complicated by the type of measuring sample. In particular, foreign atom portions in crystals (doping) are difficult to recognize in the diffraction spectrum and amorphous sample portions or multiple scattering may also falsify the analysis.
To facilitate the qualitative analysis of measuring samples, an element spectrum of the measuring sample is conventionally acquired, e.g. using X-ray fluorescence (XRF) (compare R. Meier cit. loc.). Phases which would require chemical elements which are not detected in the sample can be omitted in the qualitative phase analysis using information concerning the element concentrations in the sample. Use of the element spectrum increases the reliability of the qualitative phase analysis of the diffraction spectrum. Only the phases selected in the qualitative phase-analysis are then included in the quantitative phase analysis of the diffraction spectrum.
In this conventional analytical method, the result of the quantitative phase analysis of the diffraction pattern is often quantitatively incompatible with the measured element concentrations determined from the element spectrum. Determination of the phase portions of the crystallographic phases from the diffraction pattern is therefore incorrect.
Departing therefrom, it is the object of the present invention to provide a more reliable quantitative phase analysis of a measuring sample.